Andrii RomasiunBlog

Andrii Romasiun

I am a senior software engineer based in London with over six years of building production software across backend, frontend, and AI. I design systems that stay fast under load, and I care about the details users never see.

I am open to new opportunities and hard problems worth solving. I hold a UK Global Talent visa, so I need no sponsorship to work in the UK.

I write on my blog and build in the open on GitHub. You can also find me on X and LinkedIn, or send me an email at [email protected].

What I do

I build backend, frontend, and AI systems for startups and product teams. I take on full-time and part-time roles, as well as contract and consulting engagements.

Backend and APIs: Node and NestJS services, REST and GraphQL, with PostgreSQL, MySQL, Redis, and ClickHouse.
Frontend: TypeScript and React, built with React Router and Next.js.
AI engineering: RAG, LLM-powered workflows, and long-running orchestration with Temporal and Inngest.
Scale and reliability: High-throughput, event-driven systems that stay fast and predictable under heavy load.

Things I have built

SwetrixOpen-source web analytics

A privacy-first, open-source analytics platform I architected and still build. It serves millions of requests a day from more than 50,000 websites, with a self-hosted edition, SDKs on NPM, and developer docs.

Inset AIAI product

An AI product I designed and built from scratch, bringing practical, LLM-powered workflows to everyday tasks.

TapApplyJob-search tooling

A tool that helps people apply to jobs faster and stay on top of their search, built end to end.

Where I have worked

2025 to now

Full-Stack Engineer at CoLoopYC S21

Scaling an AI platform for qualitative research. Long-running AI workflows on Temporal and Inngest for transcription and analysis, plus FFmpeg video-processing pipelines.

2023 to 2025

Senior Fullstack Engineer at Strathberry

Migrated a high-traffic luxury e-commerce site from Shopify themes to Remix Hydrogen, lifting page speed, SEO, and accessibility. Built performant cached APIs and CI/CD pipelines.

2021 to now

Senior Software Engineer at Swetrix

Founded and built an open-source web analytics platform serving tens of thousands of sites. Shipped the self-hosted edition, SDKs, and documentation.

2020 to 2023

Frontend Engineer at Code & Care

Led the UI revamp of Bitfinex's algorithmic trading platform, speeding up order execution and cutting user errors. Mentored juniors and ran technical interviews.

Speaking and open source

I speak at conferences and meetups, usually about web security, performance, and the realities of building analytics at scale. My workshop Writing Secure JavaScript is open source on GitHub.

Most of what I build is in the open. Swetrix, its SDKs, and a handful of tools and experiments all live on my GitHub.

Latest writing

All posts